Text and, to a lesser degree, speech chatting systems, are generally known in the art, particularly in relation to personal computing systems. Published U.S. Patent Application Nos. 2001/0042095 A1; 2001/0011293 A1; and 2002/0023128 A1 and U.S. Pat. Nos. 6,212,548 and 6,286,034 illustrate exemplary system and user interfaces used today. A common feature of such systems is that the various conversations (or threads) are usually split out into distinct regions (or windows) on the display or screen. Furthermore, when a single thread comprises a plurality of both text and speech exchanges, such systems usually separate the two modalities. The speech is usually played over a speaker, whereas the plurality of text messages are displayed on the screen. Users have no means to reference old speech messages or distinguish when they occurred in the thread relative to other messages in that thread.
Published U.S. Patent Application No. 2002/0023128 A1 (“the '128 Publication”) describes a system where the screen area is split into six distinct windows. One window presents a chat history of one thread (the thread in focus) while another window displays a chat history of the combined plurality of the remaining threads. A chat history comprises a plurality of entries displayed on the screen that describe both inbound (i.e., received by the user's mobile terminal) and outbound (i.e., sent by the user's mobile terminal) chat messages. The entries are usually displayed on the screen in chronological order and usually only describe text messages.
Although the above-described chat systems fulfill the needs of some chat group users, they do not readily provide for integration with pre-existing mobile messaging systems. With known chat systems, during a chat session, subscribers can not conveniently contact or communicated with legacy mobile users operating outside of the chat message system. Therefore, there is a need to provide a chat system that permits chat threads between mobile users running chat applications and mobile users on legacy, out-of-band messaging systems.